class Solution {
public:
    int mySqrt(int x) {
		if(x<1)return 0;
		int left=1,right=x;
		while(left<right)
		{
			long long mid=left+(right-left+1)/2;
			if(mid*mid<=x) left=mid;
			else right=mid-1;
		 } 
		 return left;
    }
};
